This carol was traditionally sung on `Gaudete Sunday', the third Sunday in Advent. There are several interpretations available on the Internet including those by Steeleye Span by the Oxford Camerata and by Libera with a boys' choir as well as one by dwsChorale in which the words are hear particualrly clearly and which can be heard on the Wikipedia page for the song. The carol was included in the 16th century Finnish/Swedish collection, Piae Cantiones, but may have originated in Bohemia in central Europe. For more details, see the Wikipedia article and also Gaudium mundo, which explains the reference in the third stanza to the gate mentioned in the Old Testament (Ezechiel 44). This was closed after the God of Israel passed through it and would be opened again only for the Prince. The Latin is translated below word-for-word.